Mosquito trapping apparatus utilizing cooled carbon dioxide

ABSTRACT

An insect trap that utilizes a combustion chamber to produce carbon dioxide for an attractant. Combustion gasses from the combustion chamber are cooled in a conduit for the trap inlet. Thus, a single fan may be used for both drawing insects into the insect trap and for cooling the combustion chamber. Combustion gasses, after being cooled by the flow of air through the conduit connected to the trap inlet, may be further cooled by a cooling system, such as a thermoelectric device. As such, the insect trap of the present invention may be used to produce carbon dioxide, via combustion, at temperatures at or below ambient temperature.

REFERENCE TO RELATED APPLICATION

This application in a continuation application of U.S. application Ser.No. 10/360,401, filed Feb. 7, 2003, and incorporated herein byreference.

TECHNICAL FIELD OF THE INVENTION

The present invention relates to insect traps, and more particularly todevices for attracting, and trapping or killing, mosquitoes and otherbiting insects.

BACKGROUND OF THE INVENTION

Biting insects, such as mosquitoes and flies, can be an annoying,serious problem in man's domain. They interfere with work and spoilhours of leisure time. Their attacks on farm animals can cause loss ofweight and decreased milk production. Worldwide, mosquito-borne diseaseskill more people than any other single factor. Mosquitoes can becarriers of malaria, yellow fever, and dengue fever in humans. In theUnited States, mosquitoes spread several types of encephalitis,including the West Nile virus. They also transmit heart worms to catsand dogs.

People are not the primary blood hosts for mosquitoes and bitinginsects, especially in temperate climates. The major mosquito pests inthe southeastern United States seem to prefer the host-odor of smallherbivorous (vegetarian) mammals, such as rabbits, or birds. Mosquitoesthat carry encephalitis seem to prefer avian (bird) blood hosts. Thesemosquitoes bite people when they get the chance, but they are better attracking the scent of animals that are most abundant in their habitat.

People have tried a number of different methods to rid themselves ofmosquitoes and other biting insects. One method that is often utilizedis spraying or applying chemical insecticides. Although many chemicalswork well to kill or repel mosquitoes, the chemicals often have adeleterious effect on the environment, including, but not limited to,killing beneficial insects. In addition, chemical insecticides areeffective only for a limited amount of time, and thus must becontinuously sprayed. Moreover, many types of mosquitoes and bitinginsects are capable of developing resistance to the chemical pesticidesin a few generations (which may only take a few months for mosquitoes),and in the long run, that adaptation makes the species stronger.

Another method used to combat mosquitoes is bug zappers. In general, abug zapper includes a fluorescent light source surrounded by anelectrified grid. The theory behind these devices is that the mosquitoesare attracted to the light, and, upon flying to the light, will beelectrocuted by the grid. In actuality, however, the bug zappers killbeneficial insects, and attract mosquitoes but does not kill them insignificant numbers.

Citronella candles and smoking coils are often used to repel mosquitoesand other insects. However, research has shown that, in general, anindividual must stand within the smoky plume of the citronella to beprotected. This, of course, is not desirable. Moreover, even whenstanding in the plume, citronella is only partly effective in reducingthe probability of a mosquito bite. Encouraging natural predation ofinsects by setting up bird or bat houses in the backyard has also beenunsuccessful in reducing local mosquito populations.

Recently, significant research and effort have been expended to developdevices that attract and trap or kill mosquitoes. In general, thesedevices attempt to replicate the mosquito-attracting attributes of atypical blood host, such as a rabbit or a bird. Mosquitoes locate bloodhosts by scent, sight and heat. From 100 feet away (30meters) mosquitoescan smell a potential blood host's scent, especially the carbon dioxide(CO2) the blood host exhales. Similarly, biting flies can smell theirprey from 300 feet (100 meters) away. Because CO2 is present in theatmosphere (plants take in CO2 and give off oxygen), mosquitoes respondto higher-than-normal concentrations, especially when the CO2 is mixedwith host-odor. They follow a blood host's scent upwind, and can see atarget at a distance of about 30 feet (10 meters). Devices that try tosimulate a mosquito host thus may include, for example, a source ofcarbon dioxide, a source of octenol (an alcohol that is given off bymammalian blood hosts), and/or a heat source.

One such device is sold under the trademark “MOSQUITO MAGNET” and isdescribed in U.S. Pat. No. 6,145,243 to Wigton et al. The MOSQUITOMAGNET apparatus is an insect trapping device that generates its owninsect attractants of carbon dioxide (CO2), heat, and water vaporthrough catalytic conversion of a hydrocarbon fuel in a combustionchamber. The hot insect attractants generated in the combustion chamberare diluted and cooled to a temperature above ambient temperature andbelow about 115 degrees Fahrenheit (F) by mixing with air, and themixture is exhausted downward through an exhaust tube. A counterflow ofoutside air is drawn into the trap though a suction tube thatconcentrically surrounds the exhaust tube. Biting insects are suckedinto the suction tube and are captured in a porous, disposable bagconnected to the other end of the suction tube. Additional chemicalattractants may be used with the device to make the trap even moreeffective.

Although the MOSQUITO MAGNET device works well for its intended purpose,due to its high suggested retail price ($500 to $1300, depending uponthe model), it is far out of reach of the ordinary consumer. Thus, fewpeople would actually purchase the MOSQUITO MAGNET, even if they have apressing need for mosquito control.

Another device that has been used in the past for trapping mosquitoes isthe Center for Disease Control (CDC) light trap. The light trap includesa motor driven rotary fan to move attracted insects down into a holdingcontainer suspended beneath the trap, and a light source. More recently,the CDC light trap has been used with a source of carbon dioxide,usually dry ice. Dry ice produces carbon dioxide at a temperature belowambient, and works particularly well for attracting mosquitoes and otherbiting insects. Although a CDC light trap utilizing dry ice works wellfor its intended purpose, the handling and use of dry ice can bedifficult and expensive.

SUMMARY OF THE INVENTION

The present invention provides an insect trap that utilizes a combustionchamber to produce carbon dioxide for an attractant. Combustion gassesfrom the combustion chamber are cooled in a conduit for the trap inlet.Thus, a single fan may be used for both drawing insects into the insecttrap and for cooling the combustion chamber.

In accordance with an aspect of the present invention, combustiongasses, after being cooled by the flow of air through the conduitconnected to the trap inlet, may be further cooled by a cooling system,such as a thermoelectric device. As such, the insect trap of the presentinvention may be used to produce carbon dioxide, via combustion, attemperatures at or below ambient temperature.

Other advantages will become apparent from the following detaileddescription when taken in conjunction with the drawings, in which:

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic representation of an insect trap in accordancewith the present invention;

FIG. 2 is a side perspective view of a combustion gas cooling portionthe insect trap of claim 1;

FIG. 3 is an exploded side perspective view showing the combustion gascooling portion of FIG. 2; and

FIG. 4 is an exploded side perspective view showing the combustion gascooling portion of FIG. 2, in a further state of disassembly, and withparts removed to show detail.

DETAILED DESCRIPTION

In the following description, various aspects of the present inventionwill be described. For purposes of explanation, specific configurationsand details are set forth in order to provide a thorough understandingof the present invention. However, it will also be apparent to oneskilled in the art that the present invention may be practiced withoutthe specific details. Furthermore, well-known features may be omitted orsimplified in order not to obscure the present invention. In addition,to the extent that orientations of the invention are described, such as“top,” “bottom,” “front,”“back,” and the like, the orientations are toaid the reader in understanding the invention, and are not meant to belimiting.

At the outset, it is important to note a few characteristics ofmosquitoes and flying insects. Typically, biting insects are attractedby the odor of kairomones, which are chemicals given off by blood hostsand which are attractants to biting insects. Kairomones include carbondioxide exhaled by both mammalian and avian blood hosts and octenol, analcohol which is given off by mammalian blood hosts. Biting insectslocate a blood host by tracking the odor plume created by the bloodhost. A mixture of carbon dioxide and octenol is particularly attractiveto insects seeking mammalian blood hosts. The present invention providesa relatively inexpensive way to provide cooled carbon dioxide for amosquito trap, and specifically may provide carbon dioxide at or belowambient.

Turning now to the drawings, in which like reference numerals representlike parts throughout the several views, FIG. 1 shows a schematicdiagram of an insect trap 10 incorporating the present invention. Theinsect trap 10 includes a trap inlet 12 at an end of a trap conduit 14.In accordance with one embodiment of the present invention, a combustionchamber 16 is mounted in the trap conduit 14, and is cooled by air flowthrough the trap conduit.

Briefly described, combustion occurs in the combustion chamber 16, andthe combustion gasses from the combustion process are cooled by airflowing through the trap conduit 14. The cooled air flows from thecombustion chamber 16 into a cooling chamber 18, and out of exhaustoutlets 20. The cooling of the combustion chamber 16 by the air flowingthe trap conduit 14, along with the cooling by the cooling chamber 18,causes the gasses exiting from the exhaust outlets 20 to be at or belowambient temperature.

The invention has particular use for producing cooled carbon dioxidegasses for use in a mosquito trap. To this end, the trap inlet 12 mayserve as an inlet for receiving mosquitoes and other biting insects thatare attracted by the exhaust plume exiting the exhaust outlets 20. Thus,in accordance with one aspect of the present invention, the exhaustoutlets preferably route the cooled, combusted gasses adjacent to thetrap inlet 12. Mosquitoes attracted to the plume are drawn into the trapinlet 12.

To capture mosquitoes and/or biting insects, the insect trap 10 mayinclude a specimen bag 22 at some position along the length of the trapconduit 14 for catching insects as they are drawn through the trapconduit 14. To this end, a fan 24 or a similar device that is capable ofdrawing air through the trap conduit 14 is provided within, or isotherwise associated with, the trap conduit 14 so as to draw air throughthe trap conduit 14.

In one embodiment, the fan 24 may be capable of drawing, for example,235 cubit feet per minute of air through the trap conduit 14. Thissignificant draw of air into the trap inlet 12 is sufficient to drawmosquitoes and other biting insects into the trap conduit 14 when theinsects approach the trap inlet 12.

In accordance with one aspect of the present invention, the combustionchamber 16 is mounted so that the combustion chamber, and gassesproduced in the combustion chamber, are cooled by air flowing from thetrap conduit 14. In the embodiment shown, the combustion chamber 16 islocated in the trap conduit, but air may alternatively be routed intocontact with combustion chamber, such as against the side of thecombustion chamber, or through a portion of the combustion chamber. Tothis end, to the extent that the trap conduit 14 is discussed herein asrouting air over, through, in contact with, or around the combustionchamber, the air flow may be any of these. Similarly, the trap conduit14 may not be a single conduit, but instead may be any structure thatdirects at least some air from the trap inlet into contact with thecombustion chamber.

In the embodiment shown in the drawings, the combustion chamber 16includes a burner tube 30. Details of the burner tube 30 are best shownin FIG. 4. The burner tube 30 includes a right angel bend at its lowerend, with first and second fans 32, 34 at opposite ends of the rightangle. The fans 32, 34 are both arranged so that they may draw air intothe burner tube 30, and in one embodiment, each produces an air flow ofseven to ten cubic feet per minute. As an alternative to the two fansshown, a single fan may be used to draw air into and through the burnertube 30.

A burner 36 is mounted centrally in the burner tube 30. Preferably, theburner is spaced from the inner side walls of the burner tube 30. Theburner 36 includes a fuel inlet 38 leading to typical components for aburner assembly, for example, such as is used for camping stoves orcamping lanterns. Because such components are well known, they areomitted from the drawings in order not to obscure the present invention.However, as an example, the fuel inlet 38 may be connected to aregulator (not shown) for lowering the pressure from a propane tank orother propane source. Although described with reference to a propaneburner, the combustion chamber 16 may utilize other fuels forcombustion, including, but not limited to, kerosene, gasoline, and otherliquid, solid, or gaseous fuels.

An electrode 48 (FIG. 4) may be included for starting a flame in theburner 36 in a method known in the camp stove art. Alternatively, manuallighting of the burner 36 may be implemented, but such a system is notas convenient as a burner including an automatic starter such as theelectrode 48.

In the embodiment shown in the drawings, the fans 32, 34 draw airthrough the bottom of the burner tube 30 into contact with the bottom ofthe burner 36 and around the burner 36 to bypass the burner 36. Airentering the burner 36 is used in the combustion process. Air flowingaround the burner 36 is not combusted. Preferably, in accordance withone aspect of the present invention, a structure is provided within theburner tube 30 or closely associated therewith that mixes the combustedgasses from the burner 36 with the air flowing around the burner 36. Inthe embodiment shown in the drawings, this mixing is provided by acircular pattern of fixed fan blades 40 (FIG. 4) positioned across thetop of the burner tube 30. However, if desired, other structures may beused.

A cylindrical heat exchanger 50 is mounted on the outside of the burnertube 30. The cylindrical heat exchanger 50 is preferably formed of athermally conductive material. In the embodiment shown in the drawings,the cylindrical heat exchanger 50 includes a central cylinder 52 havingouter fins 54 extending outwardly therefrom. Inner fins 56 extend inwardfrom the central cylinder 52 and are spaced from one another so as toform a void. The void is sized and arranged so as to receive the burnertube 30. The burner tube 30 preferably fits within the void so that thetop of the burner tube 30 is spaced from the top of the cylindrical heatexchanger 50, the function of which is described below. If desired, theburner tube 30 may alternatively be integrally formed with the heatexchanger 50.

In the embodiment shown in the drawings, a series of bosses 58 arelocated around the top edge of the central cylinder 52. The bosses arefor receiving fasteners 59 for the attachment of a top plate 60. The topplate 60 encloses the top portion of the central cylinder 52, and withthe central cylinder defines a central chamber in the heat exchanger.The central chamber may be arranged in alternate ways. Although shown asa cylinder with a flat top in the drawings, the central chamber may takeany shape and may be formed from one or more pieces. The top portion ofthe burner tube 30 is located within the central chamber. Although shownas being attached by the fasteners 59, the top plate 60 may be one piecewith the cylindrical heat exchanger 50, or may be attached in anothersuitable manner, such as welding.

A series of flanges 62 extend outward from a bottom portion of thecylindrical heat exchanger 50. As can be seen in FIG. 4, the electrode48 may extend out of the side of the cylindrical heat exchanger 50.

As shown in FIGS. 3 and 4, to assemble the combustion chamber 16, theburner tube 30 is inserted upward into the void between the innerflanges 56 of the cylindrical heat exchanger 50. The cylindrical heatexchanger 50 is then inserted into the trap conduit 14. Preferably, eachof these pieces fits tightly into the next, so that the outer edges ofthe outer fins 54 of the heat exchanger 50 engage the inner walls of thetrap conduit 14, and the burner tube 30 abuts the inner edge of each ofthe inner fins 56. In the shown embodiment, the trap conduit 14 is splitinto two different pieces, with the fan 24 being situated between thetwo pieces. If desired, the trap conduit 14 may be formed as a singlepiece, or as multiple pieces, or may be any structure that providesfluid communication between the trap inlet 12 and the combustion chamber16.

When the cylindrical heat exchanger 50 is inserted into the trap conduit14, the bottom edge of the trap conduit 14 rests against the flanges 62.Thus, the bottom portion of the cylindrical heat exchanger 50 extendsout of the bottom of the trap conduit 14.

As can best be seen in FIG. 1, the cooling chamber 18 is connected tothe bottom of the cylindrical heat exchanger 50 and is in fluidcommunication with the central chamber of the cylindrical heat exchanger50. Thus, the cooling chamber 18 is in fluid communication with theinside of the burner tube 30. The cooling chamber 18 includes a manifold68 that extends from the cylindrical heat exchanger 50 to the exhaustoutlets 20.

A cooling device is located within the cooling chamber 18. In the shownembodiment, the cooling device is a thermoelectric device 70. However,the cooling device may alternatively be any device that is capable ofremoving heat from the cooling chamber 18, such as a Stirling cooler, arefrigeration unit, or other structures designed to remove heat.

For the thermoelectric device 70, one or more thermoelectric coolers 72(FIG. 4, well known in the industry) are mounted between a cold sidesink 74 and a hot side sink 76. As can be seen in FIG. 3, the cold sidesink 74 is mounted inside the cooling chamber 18, and the hot side sink76 extends outside of the cooling chamber 18. A number of power ports 78are included on the side of the manifold 68 for attaching a power supply(not shown) to the thermoelectric coolers 72.

For the embodiment shown in the drawings, six exhaust outlets 20 areincluded on the end of the manifold 68. Any number of exhaust outletsmay be used, and exhaust from the exhaust outlets 20 is preferablyrouted adjacent to the trap inlet 12. This routing is not shown in thedrawings, but may be provided by appropriate conduits. By routing thecooled exhaust gases adjacent to the trap inlet 12, mosquitoes and otherbiting insects may be attracted by the exhaust, and may be sucked intothe trap inlet 12. A drip tube 80 is included on the bottom of themanifold 68 for allowing condensation from the exhaust to drip out ofthe manifold 68.

In operation, the fans 24, 34 and 32 are turned on, and the gas suppliedto the burner 36 via the fuel inlet 38. The electrode 48 is sparked,causing a flame to burn in the burner 36. Air may be drawn into theburner tube 30 via air inlets 82, or the air may be supplied solely fromthe fans 32 and 34. In addition, if desired, octenol or another insectattractant may be introduced into the burner tube 30 and mixed with thecombustion gases.

Combustion by the burner 36 creates carbon dioxide, which flows upwardthrough the burner tube 30. The air flow from the fans 32, 34 flowsaround the burner 36 and the combusted gasses of the burner. Becausethis air stream is under some pressure, and the combustion gasses areinitially at high heat and tend to rise, there is little mixing of theair flowing around the burner and the combustion gases until the airflow and the combusted gasses reach the fan blades 40. These fan bladescause turbulence in the air flow, and mix the combusted gasses with theair flow from the fans 32, 34. The air flow then reaches the top plate60 and is forced down between the inner fins 56 and out into themanifold 68.

Air flowing through the trap conduit 14 enters the trap inlet 12 andflows through the specimen bag 22 and through the fan 24. From there,the air has only one place to travel, and that is downward through theouter fins 54. This air flow causes a cooling of the outer fins 54. Thiscooling effect is transferred to the rest of the cylindrical heatexchanger 50, because, as stated above, the cylindrical heat exchanger50 is preferably formed of a thermally conductive material. The coolingby the air is transmitted to the burning tube 30 via the inner fins 56.To this end, the inner fins 56 may be configured (e.g., chamfered) asdesired so as to maximize heat removal from the central chamber and theburner tube.

Thus, the air flow through the trap conduit 14 cools the combusted airleaving the burner tube 30 and flowing to the manifold 68. In oneembodiment, this cooling effect, along with the cooling of the combustedgasses by the dilution with the air flowing from the fans 32, 34, causesair entering the manifold 68 to be approximately twenty degreesFahrenheit (F) above ambient.

The cooling device (e.g., the thermoelectric device 70), further coolsthe combusted gasses before they reach the exhaust outlets 20. In theshown embodiment, the combusted gasses are cooled to slightly belowambient. This temperature of carbon dioxide has been found to bebeneficial in attracting biting insects and mosquitoes.

The concepts of the invention may be used as shown in the drawings, orthe cooling chamber 18 and the cylindrical heat exchanger 50 may be usedwithout the other. For example, the burner tube 30 and the cylindricalheat exchanger 50 may be used with the trap conduit 14, without the useof the cooling chamber 18, so as to provide cooled carbon dioxide for amosquito and biting insect trap. In addition, combustion gasses may berouted through a cooling chamber, such as the cooling chamber 18, andmay be cooled by the cooling device (e.g., the thermoelectric device70), without being first cooled by the air flowing through the trapconduit 14. However, the combination of the devices works particularlywell in providing cooled combustion gasses with an apparatus of verylittle cost.

The present invention is particularly useful in that it generates carbondioxide through a combustion process, which is a relatively inexpensiveand virtually maintenance free manner of producing the carbon dioxide.In addition, the present invention utilizes an existing air flow—theflow through the trap conduit 14—to cool that carbon dioxide to atemperature where it is useful for attracting mosquitoes and otherbiting insects.

The cooling device (e.g., the thermoelectric device 70) is useful inthat it may be used to closely set an exhaust temperature for thecombustion gases. If desired, the cooling device may be used inconjunction with a temperature sensor so that exhaust temperatures maybe more precisely controlled.

Other variations are within the spirit of the present invention. Thus,while the invention is susceptible to various modifications andalternative constructions, a certain illustrated embodiment thereof isshown in the drawings and has been described above in detail. It shouldbe understood, however, that there is no intention to limit theinvention to the specific form or forms disclosed, but on the contrary,the intention is to cover all modifications, alternative constructions,and equivalents falling within the spirit and scope of the invention, asdefined in the appended claims.

1. An insect trap comprising: a trap for insects; a device for producingcarbon dioxide for attracting insects to the trap, the device forproducing carbon dioxide being in fluid communication with an attractantoutlet; and a cooling device between the device for producing carbondioxide and the attractant outlet, the cooling device including at leasta portion below ambient temperature.
 2. The insect trap of claim 1,wherein the device for producing carbon dioxide comprises a combustionchamber.
 3. The insect trap of claim 1, wherein the cooling devicecomprises a thermoelectric device.
 4. The insect trap of claim 3,wherein the thermoelectric device comprises a hot sink and a cold sink,and wherein the cold sink is arranged to contact gasses flowing throughto the attractant outlet.
 5. The insect trap of claim 1, wherein thecooling device is configured to cool gasses flowing through to theattractant outlet to ambient temperature or below.
 6. The insect trap ofclaim 5, wherein the cooling device is configured to cool gasses flowingthrough to the attractant outlet to below ambient temperature.
 7. Aninsect trap comprising: a trap for insects; a device for producingcarbon dioxide for attracting insects to the trap, the device forproducing carbon dioxide being in fluid communication with an attractantoutlet; and a thermoelectric device between the outlet of the device forproducing carbon dioxide and the attractant outlet, the thermoelectricdevice being configured to cool gasses flowing to the attractant outlet.8. The insect trap of claim 7, wherein the thermoelectric devicecomprises a hot sink and a cold sink, and wherein the cold sink isarranged to contact the gases.
 9. The insect trap of claim 7, whereinthe device for producing carbon dioxide comprises a combustion chamber.10. The insect trap of claim 7, wherein the thermoelectric device isconfigured to cool gasses flowing through to the attractant outlet toambient temperature or below.
 11. The insect trap of claim 10, whereinthe thermoelectric device is configured to cool gasses flowing throughto the attractant outlet to below ambient temperature.
 12. An insecttrap comprising: a device for producing carbon dioxide and having anoutlet in fluid communication with an attractant outlet; and a coolingdevice mounted between the outlet of the device for producing carbondioxide and the attractant outlet, the cooling device being configuredto cool gasses from the device for producing carbon dioxide to belowambient temperature.
 13. An insect trap comprising: a device forproducing carbon dioxide and having an outlet in fluid communicationwith an attractant outlet; and a thermoelectric device mounted betweenthe outlet of the device for producing carbon dioxide and the attractantoutlet, the thermoelectric device being configured to cool gassesflowing to the attractant outlet.
 14. The insect trap of claim 13,wherein the thermoelectric device comprises a hot sink and a cold sink,and wherein the cold sink is arranged to contact the gasses.
 15. Theinsect trap of claim 13, wherein the thermoelectric device is configuredto cool gasses flowing to the attractant outlet to ambient temperatureor below.
 16. The insect trap of claim 15, wherein the cooling device isconfigured to cool gasses flowing to the attractant outlet to belowambient temperature.